Is it taboo to start by asking what level the hiring manager has me pegged for, to get an idea of the pay band so I can give them a target desired salary? The offer came initally with no numbers, just a phone request.
You HAVE to ask that before. In fact if they don't tell you upfront don't bother. Things like this signal company culture, it means that they don't understand their needs in the org.
No, you can and should ask about that